I know its a bit delayed and you probably have it by now......
I'm tyring to make this for thanksgiving and the link on martha stewart is broken but I found the reciepe by googling it :)

Mrs. Milman's Chocolate Frosting

While this frosting is cooling, you'll need to stir it as instructed; otherwise, the frosting around the edge of the bowl will harden and the frosting at the center will remain liquid. The finished frosting should have a consistent texture. Lois Milman, the creator of the frosting, always uses Nestl; morsels and makes only one batch at a time. Spread the icing on Moist Devil's Food Cake as soon as it is sufficiently chilled; it holds its shape well on the cake.